Checked it in IE11 on my end and they don't show up here either (but I don't get any script errors in the console either). Looks like microsoft broke something, works fine in chrome/firefox/edge. I'll see if I can dig up anything after work.

Funny thing, hit F12 in IE, then switch back to the main window without minimizing the developer tools window, and refresh one of these pages with the embedded video.

Also, the script error is on youtube inside the iframe, not local to this page. So it appears google broke it, I'm still trying to find something other than keeping the developer tools open in the background that fixes it. I will update the thread if I find anything.